DE1232437B - Weight compensation device for the tool carrier head of a machine tool - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

B23c

German class: 49 b -4/06

Number: 1232437

File number: G 204481 b / 49 b

Filing date: September 1, 1956

Opened on: January 12, 1967

The invention relates to a weight compensation device for the tool carrier head Machine tool, in particular milling machine, in which the tool carrier head is vertically movable on one suspended cross beam is slidably guided and its weight by a also vertical movably suspended girder is added, on which he is vertically resilient with a Trolley is longitudinally displaceable.

Weight balancing devices of this type are for machine tools with two vertical ones Uprights and a cross beam running horizontally and parallel to the support beam known, wherein the tool carrier head is vertically resiliently displaceable with a trolley on the carrier beam is. Because of the possibility of longitudinal displacement of the tool carrier head between the two vertical uprights and the vertical ones that are also necessary to carry out many operations Up and down movement of the tool carrier head is caused by such machine tools the weight of the tool carrier head significant weight shifts that tilt and Can cause bending of the tool carrier head supporting beam.

Known weight compensation devices are therefore used to compensate for the horizontal and vertical movement of the tool carrier head occurring weight shift has been sought, about the possible accuracy of the setting of the machine tool and the work to be performed and to ensure premature wear of the machine as a result of uneven loading to avoid individual machine parts.

A known device of this type consists of a cable construction, one horizontally arranged Support beam is held at the upper ends of the vertical upright by means of brackets and a trolley moving the tool carrier head along the carrier beam is provided during the weight shift occurring during the longitudinal displacement of the tool carrier head Tension ropes are compensated, which are connected to the tool carrier head and via corresponding Roller assemblies carry vertically movable counterweights.

This balancing device has the disadvantage that because of the necessary tensioning ropes and the associated balancing weights, a large amount of space is required, especially in the horizontal and vertical movement of the tool carrier head appropriately sized and for the free weight balancing device for the
Tool carrier head of a machine tool

Applicant:

Giddings & Lewis Machine Tool Company,

Fond du Lac, Wis. (V. St. A.)

Representative:

Dr.-Ing. H. Ruschke, patent attorney,

Berlin 33, Auguste-Viktoria-Str. 65

Named as inventor:

Jesse Daugherty,

Fond du Lac, Wis. (V. St. A.)

Claimed priority:
V. St. v. America September 2, 1955
(532172)

Suitable spaces must be available for the tension ropes to pass through. This requires the attachment of additional Deflection rollers and increases the overall manufacturing effort for the machine tool. In addition comes that the balance weights must be sized accordingly, so that the total weight the machine tool increased very much. There is also the risk that the used Tension ropes wear out heavily with prolonged use and are therefore prone to failure.

The object of the invention is to provide a weight compensation device for tool carrier heads of machine tools that have the above-mentioned disadvantages of a tension rope construction avoids. For this purpose, the invention provides a hydraulically operating compensation device before, the solution of the task in detail by housed in the stands, on one side loaded with hydraulic fluid and bearing the support beam piston gear takes place, the hydraulic fluid can be controlled by two control slides, the piston of which is controlled by a relative movement of the crossbeam are displaceable relative to the support beam.

For the vertically flexible suspension of the tool carrier head is according to the invention on the trolley a piston gear arranged on which on

609 757/197

the underside of the piston, which is acted upon by hydraulic fluid, is suspended from the tool holder head.

The invention is explained in more detail below with reference to the drawing, for example. The chosen Embodiment represents a milling machine with two slidably guided on a crossbeam Tool carrier heads. It shows

F i g. 1 is a perspective view of a milling machine with the weight compensation device according to the present invention,

F i g. 2 is a front view - partly in section - of the milling machine with the compensation device according to the invention,

F i g. 3 a sectional view of the piston gear arranged on the trolley of the milling machine,

F i g. 4 a schematic representation of the hydraulic line routing of the compensation device according to the invention,

F i g. 5 shows an enlarged illustration of a control slide in a top view along line 7-7 of FIG. 2,

F i g. 6 is a front view of the control slide along line 8-8 of FIG. 5 and

7 shows an enlarged section through the control slide according to section 9-9 of FIG. 5.

The milling machine according to the invention comprises a machine bed 20 (FIGS. 1 and 2) on which a work table 22 rests, which can be moved in a straight line in the guide 24. Two uprights 26 extend from opposite sides of the machine bed 20 upwards and are on their outer sides with guide rails 27 for holding and guiding a vertically movable cross beam 28 is provided. The transom 28 has horizontal guides 30 in which, in the illustrated embodiment, two tool carrier heads 32 and 33 are guided horizontally.

The weight of the tool carrier heads is also suspended vertically movable by a Support beam 38 added, the above the cross beam 28 and parallel to this by means of two Roller chains 40 and 41 or the like. Is suspended. As can be seen from FIG. 2, each tool carrier head is suspended vertically resiliently on a piston rod 74 of the piston 72 (FIG. 3) of a piston gear 48, which is attached to a trolley 50, which can roll along on rails of the support beam 38.

By supplying pressure fluid to the cylinder 70 of the piston transmission 48 through a cylinder located therein Opening 76 is, as FIG. 3 shows, a force-fit supporting effect is achieved so that on the Piston 72 a lifting force is exerted.

The pressure fluid is supplied to the cylinders 70 under a pressure which is sufficient to generate a lifting force exert on the piston 72, which is equal to the total weight of the corresponding tool carrier heads 32 and 33 and part of the weight of the crossbar 28 is. The rest of the weight of the crossbeam is carried by the height feed spindles 79 (FIG. 1) which are adjacent to the uprights 26 27 are attached to their vertical guides. The piston 72 remains with respect to the cylinder 70 in a static position as long as there is no change in either the pressure of the lifting fluid or in the combined weight of the tool carrier heads carried and the mentioned part of the crossbeam takes place.

If, for example, the height feed spindles 79 (FIG. 1) are rotated in such a direction that If the crossbeam and the tool carrier heads are lifted vertically, they would have a larger one Take up part of the combined weights of the tool carrier heads and the crossbeam and thereby cause an imbalance in the forces acting on the pistons 72. If this Hebewirkong occurs, the pistons are lifted by the action of the hydraulic fluid on their underside, with some liquid in the cylinders 70 above the piston 72 through an opening 80 into a Drain line 82 is drained. On the other hand, the crossbeam and the tool carrier heads lowered by the spindles 79, so that of the tool holder heads and the crossbeam is on downward force exerted on each piston increases, thereby increasing the pressure exerted by the hydraulic fluid upward force is overcome and each piston 72 in its corresponding Cylinder 70 moved down.

The piston gear 48 is the hydraulic fluid through a main pressure line 78 by means of one of A hydraulic pump 84 driven by an electric motor 85 (FIG. 4) is supplied. In the present In this case, a two-pressure vane pump is used as the pressure fluid source, which is suitable for pressure fluid either under high pressure at low volume or under low pressure at large Deliver volume. The high-pressure side of the pump 84 with a small volume is shown at 84 a, while the low-pressure side with a large volume shown at 84 &. However, other types of pumps can also be used, as the two-pressure version is shown for the purpose of illustration only.

The pressure of the fluid supplied to the piston gear 48 can be regulated by means of an adjustable Pressure relief valve 86 takes place in order to act on the pistons 72 through the tool carrier heads 32 and 33 and balance the force exerted on the transom. The pressure relief valve 86 has a valve piston 87 on, which is arranged in a chamber 88 such that it can be moved back and forth. The valve is used to reduce the pressure in the system to drain if this exceeds a certain value that of the valve piston below Pressure holding spring 89 is determined. The hydraulic fluid outlet side The pump 84 is located with a distributor 90 in a line connection block 92 via a main pressure line 94, while the pressure relief valve is connected to this pressure line 94 is in communication via a branch line 96, so that any overpressure occurring therein is caused by the Pressure relief valve and a drain line 95 is drained into a liquid collection basin 97. the end the main pressure manifold 90 leads a pressure line to a second distribution valve 100, which is located on the Support beam 38 is located and the piston gears 48 supplies hydraulic fluid. For the purpose of the outlet of fluid from the piston gears 48 is the conduit connector block 92 described above furthermore provided with an emptying manifold 102 which is connected to the collecting basin 97 via a line 106 and in communication with the drain lines 82 from the cylinders 70 via a common line 108 stands.

In order to use the low pressure side of the hydraulic pump with a large volume if necessary, a controlled drain valve 110 is provided to the direction of the pressure fluid from the

To control the high pressure side 84 α of the pump 84. The drain valve 110 (FIG. 4) is essentially a controlled three-way valve, a valve piston 111 being set so that the flow of the pressure fluid from the low pressure side 84 b of the pump 84 is passed directly through the drain line 95 to the collecting basin 97 when the high pressure side of the pump is sufficient to operate the hydraulic piston gear. However, is a higher fluid

the can, wherein an outlet opening can be closed by a plug 165 to the To set up the control slide for use in the present control system.

It can be seen that since the tool carrier heads 32 and 33 are slidable on the crossbeam 28 are stored, are resiliently suspended on the trolleys 50 and on the support beam 38 frictionally a suitable arrangement

volume required than the high pressure side of the io must be provided to ensure that the

Pump can deliver, an electromagnet 112 is actuated and moves a control valve piston 114 a three-way control valve 115 in such a way that high-pressure liquid to the control valve surface 116 of the drain

Support beam 38 to lie at a given distance above the crossbeam and parallel to it comes. This arrangement consists of upstanding supports 166 (Figures 2 and 4) at each end

Let valve Ϊ10 through a control fluid line 15 of the crossbar 28, which with a cam surface 168 118 is directed. This control pressure moves the control slide on the depending valve stem 148 142 and 143 come into engagement. Appropriate adjustments are provided on supports 166 (Fig. 6)

directions provided, such as an adjustment

Valve piston 111 of the drain valve 110 in a position in which a pressure fluid line 122 from the
Pump 84 is in communication with the main pressure line 94, whereby a check valve 124 is bypassed screw 170 with a cam engaging surface 171, which normally controls the entry of the low-pressure as well as guide pins 172 on the supports, which are in pressure fluid in the system prevented. The KoI bearing in the support beam 38 engages ben 111 of the drain valve 110 is adjusted by a spring must act to close the position of spool 142 and 143 when the carrier drain valve piston 111 shifts. In the same bar hangs in the position in which it acts the whole way the solenoid of the control valve 115 weight of the tool carrier heads 32 and 33 and against the pressure of a spring 127 which normally holds part of the weight of the crossbar 28 on the control valve piston 114 in one position , takes. In this position, the pistons 72 float in which the control surface 116, the drain valve 110 with its corresponding cylinders 70 and offer the desired elastic connection between the collecting basin 97 via a drain line 128. Carrier beams and the tool carrier heads.

The support beam 38 is from in the uprights 26. It can be seen that the pistons of the rudder housed Carried piston-driven, the Zy slides are displaced with respect to the carrier beam by a relative movement of the transverse connector 130 with the bars 28 arranged to be movable back and forth therein Neten piston 132 include (Fig. 4), which will be when the distance between the carrier piston rods 134 upward through the cylindrical bars 38 and the transverse bar 28 become larger or smaller extend and accordingly in the ner than the distance at which the control spool in Roller chains 40 and 41 grip. To stand a vertical a closed center position. Such Relative movement of the crossbar 28 with respect to the 40 relative movement causes the pistons 146 To allow support beam 38, the pressure can either move down or up, being fluid for the mentioned piston gears by the volume of the hydraulic fluid in the two pistons Control slide 142, 143 can be influenced. exaggerated 42 and 43 is changed. If that The control spools shown in FIGS. 5, 6 and 7 changed in liquid volume, the carrier follows enlarged Scale are shown, are as three-45 bars 38 of the movement of the crossbar 28 and Directional control valves for supplying or draining the seeks a constant distance between the two Hydraulic fluid to or from the cylinders withheld. Since the movements are usually slow, forms. Each of these control spools consists of one, there is no significant lag between the Housing 144 with a two bar in a cylindrical chamber. However, the crossbar should The reciprocating piston 146 moving 50 upward in rapid traverse can so continues downward into a valve stem 148, which has a switch (not shown) which is connected to a quick

protrudes through the lower part of the housing 144. At the opposite end of the piston is a shoulder 150 is provided against which a spring 152 presses to urge the piston 146 downward gen. With both control slides 142 and 143 (FIGS. 4 and 7), a cylinder opening 154, which is provided with a Line 156 communicates with the chamber of cylinder 130 above the associated piston

running control switch is in communication, the control valve solenoid actuate to supply a large volume of pressurized fluid to the cylinders 130. With this requirement of a large hydraulic fluid volume the height feed spindles 79 instantly take the weight of the tool carrier heads on, relieve the pressure on the piston gear 132 and thus the amount of pressure in the

the piston 146 is closed when the piston is 60 cylinder 130. The pressure of the low-pressure side 84 b is in the middle position. On opposite sides of the pump 84 is therefore sufficient to supply the volume sides of the cylinder port 154 with one of the pressurized fluid that is required, pressure port 162 and a drain port 164 which lower the piston in the cylinder 130, corresponding to the pressure manifold 100 (Fig. 4) If the vertical movement of the crossbeam stops, and the drain line 108 via the lines 158 6 _S , the piston gears 132 will continue to be connected to hydraulic fluid and 160. Furthermore, the control slide shown in FIGS -

is gripped and the piston 146 is moved into the closed central position and thus effectively shuts off the pressure fluid in the cylinders 130.

The weight supported by the support beam 38 is constant for a given number of tool carrier heads. In contrast, the pressure in the cylinders 130 of the piston gears 132 changes depending on the horizontal position of the tool carrier heads on the crossbeam 28. If, for example, the distances between the tool carrier heads are symmetrical with respect to the carrier beam, the fluid pressure in each of the cylinders 130 will be approximately the same . If, on the other hand, both tool carrier heads are displaced along the crossbeam so that they are carried at one end of the carrier beam, the pressure in the cylinder closer to this end is greater in order to absorb the increased load resting on it. From this it can be seen that the cylinders act as fixed suspension members when the cylinder lines 156 are closed, the pressure therein being dependent on the position of the tool carrier heads on the crossbeam. It should also be pointed out that the hydraulic fluid pump 84 constantly generates a maximum fluid pressure which is equal to or greater than the maximum possible pressure which can be achieved in each of the two cylinders 130 in order to supply hydraulic fluid to the cylinders when required. Accordingly, the piston surfaces of both piston gears 132 and the piston gears 48 are dimensioned so that the correct amount of lifting force is generated on the suspension chains 56 or the tool carrier heads - as described above.

The feed lines including the hydraulic fluid and coolant lines 176 or the like and the various electrical power and control lines 177 branch off from a hose

housing 178 (FIG. 1) at one end of the support beam 38 . There is sufficient slack in the various feed lines between the hose housing and the end of the support beam to permit vertical movement of the support beam.

Claims (2)

Patent claims: 1.Weight compensation - device for the tool carrier head of a machine tool, in particular a milling machine, in which the tool carrier head is guided displaceably on a vertically movably suspended crossbeam and its weight is taken up by a vertically movably suspended carrier beam on which it is vertically flexible with a trolley , characterized by piston gears (132) accommodated in the uprights, acted upon by hydraulic fluid on one side and carrying the carrier beam (38), the hydraulic fluid of which can be controlled by two control slides (142, 143) , the piston (146) of which by a relative movement of the crossbar ( 28) are displaceable relative to the support beam (38). 2. Weight balancing device according to claim 1, characterized in that for the vertically resilient suspension of the tool carrier head (32, 33) on the trolley, a piston gear (48) is arranged, on whose piston (72) acted upon with hydraulic fluid on the underside of the tool carrier head ( 32, 33) is suspended. Considered publications:
German patent specification No. 913 016. For this purpose 2 sheets of drawings 609 757/197 1.67 © Bundesdruckerei Berlin